The present invention relates to apparatus for drying a moving web and, more particularly, to such an apparatus utilizing radiant heaters disposed on a frame transverse to the web.
During the process of making paper, moisture must be removed from a continuously moving paper sheet or web. This is primarily accomplished by passing the sheet or web between revolving, steam-filled cylindrical drums which convert much of the trapped moisture to steam.
Further moisture removal is commonly achieved through the use of infra-red dryer systems, which perform two primary functions. Firstly, they provide additional heat, uniformly across the moving web, thereby speeding the drying of the web and permitting a corresponding increase in the production rate. Secondly, through appropriate power control, they provide additional, localized heat to effectively dry high moisture areas which may occur at varying points across the web.
Typically, infra-red dryer systems comprise a number of lamp modules mechanically fastened to one or more support frames extending across the web. The support frames generally serve as a duct to supply cooling air to the functional components and also serve as a cable tray to deliver power to the individual lamp modules.
The modules generally each comprise a sheet metal housing, a number of electric infra-red heater lamps, an internal reflector, a protective transparent window, internal electrical connections, and integrated ducting for operational cooling. All of these components, and the various fasteners which hold them together, are subjected to intense heat and also to the effects of thermal expansion during operation. In addition, infra-red heater lamps tend to fail on unpredictable time schedules. Scheduled maintenance periods are normally brief, requiring immediate and efficient action.
Present infra-red lamp module designs are such as to require that several components, as well as various fasteners, be removed to gain access to the internal components for service. The process of removing a lamp module from a support frame, and then removing and repairing or replacing defective components, is commonly a time consuming function. Often, this results in a lack of sufficient time to service all of the lamp modules within a dryer system. Further problems may arise during servicing, when dissembled components or fasteners are subject to loss or damage.
It is, therefore, a primary object of the present invention to provide an improved web heating or drying system which avoids the aforementioned shortcomings and limitations of the prior art. More specifically, it is an object to provide such a system wherein the lamp or heater modules may be readily removed from and replaced on their support frames and wherein the various components of the individual modules may be readily removed therefrom for servicing or replacement.
It is a further object to provide such a system which utilizes a minimum number of components and fasteners, whereby the costs of system fabrication, assembly and installation may also be reduced.
The foregoing and other objects and advantages of the invention are achieved by an apparatus of the type including an elongate support frame and a plurality of heater modules releasably attached thereto, wherein the heater modules each include a housing and an inner panel assembly releasably captured therein. An openable cover, in the housing, provides for easy insertion or removal of the inner panel assembly. A plurality of lamps are operatively supported on the inner panel assembly by means which include a locking member displaceable between a first position, whereat all of the lamps are locked in position, and a second position, whereat the lamps may be removed.
More particularly, the inner panel assembly rests on two mutually perpendicular support members in the housing and is clamped against one of them by the closed cover.